1. Field of the Invention
The present invention relates to a drill head for drills, in particular for drills usable in mine and tunnel constructions, and having a bit, which can be inserted into the drill head or formed thereon, and at least one suction opening for removing drillings.
2. Description of the Prior Art
Drill heads of the type described above are used in dry drilling processes and are usually put on tubular drill pipes. The drill heads have usually a bit formed at the cutting side, or an insertable hard material bit receivable in a recess provided on the cutting side. On the cutting side, there is provided at least one suction opening that enables aspiration of drillings through the drill pipe.
A drill head of the type discussed above is disclosed, e.g., in U.S. Pat. No. 4,711,312 and has a hard material bit inserted in a recess formed in the cutting side and projecting therefrom beyond the cutting side of the drill head. At the cutting side, there are provided two diametrically opposite suction openings.
For insuring a high drilling advance, the bit projects beyond the cutting surface or side. However, the further the bit projects beyond the cutting side of the drill head the more coarse or bigger are the drillings which are produced during drilling of a bore. In addition, with high drilling speeds as, e.g., at dry drilling in carbonaceous materials, e.g., secondary material pieces, coarse drillings, are produced.
The drawback of the known drill head consists in that coarse drillings reach directly into the drill pipe through the suction openings, which can result in clogging of the drill pipe. Therefore, the drilling process has to be interrupted at least once so that in order to insure an adequate drilling process, the drill pipe is cleaned with a special tool to make the drill pipe passable again.
Accordingly, an object of the present invention is to provide a drill head which would provide for a high drilling speed and would prevent clogging of the drill pipe during suction of drillings to a most possible extent.